Press nip of a paper machine composed of a suction roll and a pressure roll

ABSTRACT

In a paper machine a paper web is conducted by a continuous felt or the like into the press nip between two rolls. One roll is a suction roll and the other roll is a pressure roll having a single pressure opening located opposite to the suction opening of the suction roll such that it does not encompass the nip between the two rolls. From the pressure opening of the pressure roll a gas, preferably heated, is conducted into the space between the rolls most appropriately before the press nip. A blocking member such as a beam with a triangular cross section may be positioned on the incoming side of the rolls to form a confined space between it and the rolls to prevent escape of the warmed, pressurized gas.

United States Patent Nykopp [151 3,655,507 Apr. 11, 1972 [54] PRESS NIP OF A PAPER MACHINE COMPOSED OF A SUCTION ROLL AND A PRESSURE ROLL [30] Foreign Application Priority Data Jan. 27. 1969 Finland ..247/69 [52] U.S. Cl ..l62/358, 34/ l 1 1, 162/206 [51] Int. Cl. ..D2lf 3/10, D2lf5/l 8 [58] Field of Search 162/358, 359, 207, 307, 305,

[56] Reterences Cited FOREIGN PATENTS OR APPLICATIONS 452,200 10/1948 Canada ..162/202 Primary Examiner-S. Leon Bashore Assistant Examiner-R. H. Tushin Attorney-Roylance, Abrams, Berdo & Kaul [57] ABSTRACT In a paper machine a paper web is conducted by a continuous felt or the like into the press nip between two rolls. One roll is a suction roll and the other roll is a pressure roll having a single pressure opening located opposite to the suction opening of the suction roll such that it does not encompass the nip between the two rolls. From the pressure opening of the pressure roll a gas, preferably heated, is conducted into the space between the rolls most appropriately before the press nip. A blocking member such as a beam with a triangular cross sec tion may be positioned on the incoming side of the rolls to form a confined space between it and the rolls to prevent escape of the warmed, pressurized gas.

6 Claims, 3 Drawing Figures SHEET 1 BF 2 PATENTED APR 1 1 I972 PRESS NIP OF A PAPER MACHINE COMPOSED OF A SUCTION ROLL AND A PRESSURE ROLL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an arrangement in suction roll presses of paper machines.

2. Description of the Prior Art In known suction roll presses of paper machines the paper web is conducted into the pressure zone or nip between two rolls and one of which is a suction roll. The paper web is conducted to the press nip supported by a felt and another felt is looped around the other roll to impact the paper web between the two felts. The lower roll is usually the suction zone beginning already before the actual press nip defined by the rolls. The water escaping from the paper web in the press nip is withdrawn through the suction opening of the suction roll.

SUMMARY OF THE INVENTION According to the invention one roll is a pressure roll having a pressure opening located opposite to the suction aperture of the suction roll to conduct gaseous pressurized fluid into the space between the rolls and preferably before the press nip.

By this means the differential pressure is increased and the removal of water through the lower felt improves.

This action may be further boosted by heating the air before it is blown out from the other roll, whereby at the same time the upper felt is warmed and the water escaping from the paper web at the press nip is warmed, its viscosity becomes less and water is also more easily transferred into the upper felt.

According to a highly advantageous embodiment of the invention, on the leading side of the press nip of both rolls there is placed a blocking member which prevents the warmed pressurized air from directly escaping from the triangular space defined between the rolls, whereby the differential pressure is accentuated and better utilization of the heat is also achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of one embodiment of the invention;

FIG. 2 shows another embodiment, partly in section and on larger scale, illustrating specifically the construction of the blocking element and the rolls; and

FIG. 3 is a perspective view of the movable blocking element with lath portions for contacting the upper belt and/or the paper web.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings, the reference numeral 1 has been employed to indicate the paper web, 2 is a flexible porous belt which is advantageously felt and referred to as the lower felt, 3 is the suction roll, 4 is a flexible porous belt which is advantageously felt and referred to as the upper felt, 5 is the upper roll blowing compressed air or steam, or the pressure roll, and 6 is the blocking member. In the embodiment presented in FIG. l, the suction roll 3 and the pressure roll 5 form a V-shaped area between the nip and the circumference of the rolls on the incoming side of the nip, the incoming side being defined as the side of the nip through which the paper web 1 passes before going through the nip itself. The blocking member 6 consists of a roll resting against the suction roll 3 and having the same length but smaller diameter than this roll and the periphery of which passes close to the upper felt 4. By this means a triangular space is formed, confined by the suction roll 3, pressure roll 5 and blocking roll 6. Of course, this space may also be closed at its ends, but it may also be left open, which may have its significance because in the drying section at all events the marginal parts of the paper web tend to dry out more efficiently. than the central part, with the result that the marginal parts of the paper web retain a higher moisture content in the press section.

Referring to FIG. 2, in connection of which the design of the suction and pressure rolls is described which is identical in both embodiments, the embodiments differing only in regard of the blocking element 6.

In the embodiment according to FIG. 2 the blocking element 6 consists of a beam with triangular cross section, e.g., a hollow beam, which has been movably mounted on the bed of the paper machine, and the edges of the beam which come into contact with the upper felt 4 or the paper web 1 having been provided with rotatable rolls or laths 7, which reduce the friction. Most advantageously a small gap may be left between the paper web 1 and the roll 7. FIG. 3 illustrates the blocking element 6 with slits 7 through the blocking element 6 between the lath portions 7 which contact the upper belt and/or the paper web.

In the embodiments displayed by both figures, the suction roll 3 has been provided with a suction aperture 8, which extends approximately from the blocking element 6 on the incoming side of the nip to a point slightly past the press nip 9. The pressure opening 10 of the pressure roll 5, however, is most advantageously somewhat smaller than the suction aperture of the suction roll positioned on the incoming side of the nip and does not extend quite up to or encompass the press nip 9, because in the nip itself water will possibly transfer also into the upper felt and into the pressure roll.

In both embodiments heated gaseous heating fluid, such as e.g., air or steam, is conducted into the pressure roll 5 and which discharges through the pressure opening 10 and through the upper felt 4 into the space above the suction aperture of the suction roll 3, whence it is drawn through the paper web and through the lower felt 2 into the suction roll through its suction aperture 8. By this means an effect is achieved which boosts the dewatering of the web 1 in three ways:

a. the upper felt 4 is warmed before its arrival in the press nip, whereby the water on entering this felt is warmed and its viscosity becomes less and its penetration is boosted,

b. the pressure is raised above the paper web, whereby the water is drawn into the suction roll more rapidly, and

c. the water in the paper web and the lower felt are warmed, lowering the viscosity of the water and thus improving the transfer of water into the felt and thence further into the suction roll.

The purpose of the blocking element is better to preserve the pressure above the suction aperture and at the same time to eliminate unnecessary heat losses in the form of heating fluid which is lost.

I claim:

1. A paper machine comprising:

a first and a second cylindrical roll, said rolls being positioned to form a press nip therebetween, said rolls also forming a V-shaped area between said rolls on the incoming side of said nip;

said first roll being a suction roll with a suction opening, said suction opening extending partially around said first roll from said press nip on the incoming side of said nip and said second roll is a pressure roll with a single pressure opening permitting a pressurized gaseous fluid to pass therethrough, said pressure opening being positioned on the incoming side of said nip and not encompassing said nip, said pressure opening permitting a pressurized gaseous fluid to enter said V-shaped area between said first and second cylindrical rolls;

an endless, flexible, porous belt contacting the surface of said first roll for at least the distance coinciding with said suction opening and passing through said press nip, said belt for supporting a paper web; and

a second endless, flexible, porous belt contacting at least the surface of said second roll on the incoming side of said press nip and passing through said press nip.

2. The paper machine in claim 1 additionally comprising:

a blocking means positioned adjacent said first and second cylindrical rolls on the incoming side, said blocking means forming a confined space between said blocking means and said first and second cylindrical rolls.

3. The paper machine in claim 2 wherein said blocking and passing through said press nip; means comprises a third cylindrical roll with a smaller diamehollow beam means movably mounted adjacent said first ter than the diameter of said first cylindrical roll, said smaller and second rolls on said incoming side of said rolls said diameter also being smaller than a diameter of said second b means b i bl to it Contact f id cylindrical roll, said third cylindrical roll being positioned ad- 5 beam to Said fi t and said Second hens, said hollow beam jacent said first and second cylindrical rolls on said incoming forming a triangular Shaped nfi d sPaCe on the i Side of 531d P- ing side of said nip between said beam, said first roll and 4. A paper machine comprising said Second 11; a fir t and a second cylindrical roll, said rolls being posiwherein said pressure opening is positioned on said incomtioned to form a press mp there between; said first roll ing Side of Said nip and not encompassing said nip, the

being a suction roll with a suction opening, said suction opening encompassing said nip and extending partially around said first roll from said press nip on the incoming side of said nip and said second roll is a pressure roll single pressure opening permitting a pressurized, gaseous l5 fluid to pass therethrough;

a first endless, flexible, porous belt, said first belt contacting the surface of said first roll for at least the distance coinciding with said suction opening and passing through said press nip, said first belt for supporting a paper web; 2

a second endless, flexible, porous belt, said second belt contacting a portion of the circumference of said second roll positioning of said pressure opening permitting said pressurized, gaseous fluid to enter said triangular shaped confined space between said beam, said first roll and said second roll.

5. The paper machine in claim 4 wherein said hollow beam additionally includes two cylindrical rolls for contacting said first and second endless belts.

6. The paper machine in claim 4 wherein the hollow beam additionally includes two lath portions for contacting said first and second endless belts. 

1. A paper machine comprising: a first and a second cylindrical roll, said rolls being positioned to form a press nip therebetween, said rolls also forming a V-shaped area between said rolls on the incoming side of said nip; said first roll being a suction roll with a suction opening, said suction opening extending partially around said first roll from said press nip on the incoming side of said nip and said second roll is a pressure roll with a single pressure opEning permitting a pressurized gaseous fluid to pass therethrough, said pressure opening being positioned on the incoming side of said nip and not encompassing said nip, said pressure opening permitting a pressurized gaseous fluid to enter said V-shaped area between said first and second cylindrical rolls; an endless, flexible, porous belt contacting the surface of said first roll for at least the distance coinciding with said suction opening and passing through said press nip, said belt for supporting a paper web; and a second endless, flexible, porous belt contacting at least the surface of said second roll on the incoming side of said press nip and passing through said press nip.
 2. The paper machine in claim 1 additionally comprising: a blocking means positioned adjacent said first and second cylindrical rolls on the incoming side, said blocking means forming a confined space between said blocking means and said first and second cylindrical rolls.
 3. The paper machine in claim 2 wherein said blocking means comprises a third cylindrical roll with a smaller diameter than the diameter of said first cylindrical roll, said smaller diameter also being smaller than a diameter of said second cylindrical roll, said third cylindrical roll being positioned adjacent said first and second cylindrical rolls on said incoming side of said nip.
 4. A paper machine comprising a first and a second cylindrical roll, said rolls being positioned to form a press nip there between; said first roll being a suction roll with a suction opening, said suction opening encompassing said nip and extending partially around said first roll from said press nip on the incoming side of said nip and said second roll is a pressure roll single pressure opening permitting a pressurized, gaseous fluid to pass therethrough; a first endless, flexible, porous belt, said first belt contacting the surface of said first roll for at least the distance coinciding with said suction opening and passing through said press nip, said first belt for supporting a paper web; a second endless, flexible, porous belt, said second belt contacting a portion of the circumference of said second roll and passing through said press nip; hollow beam means movably mounted adjacent said first and second rolls on said incoming side of said rolls, said beam means being movable to permit contact of said beam to said first and said second belts, said hollow beam forming a triangular shaped confined space on the incoming side of said nip between said beam, said first roll and said second roll; wherein said pressure opening is positioned on said incoming side of said nip and not encompassing said nip, the positioning of said pressure opening permitting said pressurized, gaseous fluid to enter said triangular shaped confined space between said beam, said first roll and said second roll.
 5. The paper machine in claim 4 wherein said hollow beam additionally includes two cylindrical rolls for contacting said first and second endless belts.
 6. The paper machine in claim 4 wherein the hollow beam additionally includes two lath portions for contacting said first and second endless belts. 